Carton box of the pivot lid type having means for snap locking the lid

ABSTRACT

The carton has a hinged top with a depending flange in the front. A panel is folded up against the inside of the depending flange. The middle of the folded up panel has an arcurate nose and the edges are adhered to the depending flange, causing the nose to bulge out slightly from the depending flange. This nose engages a slot on the front panel of the carton to lock the top in place.

The present invention relates to a carton box of the pivot lid type,typically a pastille box, having an open narrow end covered by a lidmember, which is outwardly or upwardly pivotal about a hinge line at therear side of the box, while at its three other sides it has dependinglid skirt portions which, in the closed position of the lid, projectinwardly or downwardly over the mouthing area of the box. For simplicitythe boxes will here be described as being oriented with their mouthingturned upwardly, while they will of course be usable with otherorientations.

With this kind of boxes it is a traditional problem how to make surethat the lid in its closed position is suitably locked to the box, as afree pivotability of the lid is not desirable. For avoiding unintendedopenings of the box it is required to operate with a sort of snaplocking of the closed lid, such that a certain opening force should beexerted on the lid for opening it. Such a snap locking has already beenproposed established in different manners, though each with associateddrawbacks with respect to either production or use. The boxes are massproduction objects, for which it is decisive that the production costsbe held very low, while for the practical use it is just as importantthat the said locking action will appear not only by the first openingof the box or a few openings thereafter, but rather by many followingopenings and closings.

For the boxes known so far it has been a problem that either they havebeen too expensive to produce or their integrated locking portions suchas projecting carton flaps has become deformed rather soon, that isafter only few openings and closings, in a manner such that they loosetheir snap locking effect after few operations.

It is the purpose of the present invention to provide a box which iseasy to produce in a manner such that the integrated snap locking partswill remain effective through the entire operative lifetime of the box,i.e. through many successive openings and closings of the box.

The invention is based on the recognition that a projecting locking noseportion should not necessarily be a projecting, flexible flap of thematerial, as it may well be a more spatially designed part, which mayexhibit a higher stability against being bent at all.

To be more specific, in connection with the invention it has beenobserved that on a carton portion a slightly projecting portion can beprovided by folding back an outer flap area of the material and fixingto the underlying panel only the outer side areas of the folded flap,while the intermediate part of the flap is left unfixed to the saidpanel. This bent over middle portion of the flap will thus be free toremain obliquely outstanding from the panel, by the resiliency of thematerial, provided it gets the opportunity to do this. It will have suchan opportunity if, for example, it is formed between two incisionsreaching inwardly to near the folding line, though hereby the middleportion will get the character of a pivotal flap that will not beparticularly stable. If, however, this middle flap is designed as anoutwardly arched, relatively broad tongue portion, the outer or centralend portion may, after the folding, remain pronounced projecting and yetbe in a stabilizing connection with the two fixed side areas. Thisstabilization is effective with respect to both pressing and pullingforces on the projecting edge of the tongue flap, as this flap will beshaped as a section of a cone surface that is secured along the sides,whereby it will effectively resist being pressed flat, while the outer,projecting edge portion appears on an arched surface, from which itcannot possibly be bent further out.

Thus, the outbulging locking portion or locking edge will constitute athree dimensional stabilized locking element which may maintain a goodlocking effect by many consecutive openings and closings of the box,when suitably placed thereon.

Projecting locking flaps, when used, are most commonly provided adjacentthe sides of the pivot lid, but in connection with the invention it willnormally be to prefer that the locking engagement is arranged at orbehind the middle of the front side of the lid, because this side willnormally be broad enough to accommodate the said tongue portion with awidth sufficient for the tongue end to be pronounced projecting and andyet stabilized as described. The tongue end may then cooperate with anedge portion of a slot shaped hole in the front panel of the box nearthe mouthing thereof. This also implies that the same edge portion willoccur on a broad panel, whereby it can reasonably easily yield inwardlyfor allowing the passage of the projecting locking edge when the lid isopened and closed, such that the desired lasting snap lock action can beascertained.

In the following the invention is described in more detail withreference to the drawing, in which:

FIG. 1 is a plan view of a carton blank for a box according to theinvention,

FIGS. 2 and 3 are perspective views illustrating the provision of alocking portion on the blank,

FIG. 4 is a perspective view of an erected box in its open condition,and FIGS. 5 and 6 are lateral sectional views of the box in almostclosed and fully closed condition, respectively.

The blank shown in FIG. 1, erectable to a pastille box as shown in FIG.4, will here be described in terms referring to the box orientationaccording to FIG. 4, i.e. a standing box having an upper pivot lid. Theblank and the box have a bottom panel 2, a front side panel 4 and a rearside panel 6, which is extended upwardly in a lid top panel 8 and a lidfront panel 10. Furthermore, the blank includes various side panels andcorner flaps, which will not here need any more detailed description, asthe basic design of the box is conventional. The box has a pivot lid 12,which is hinged to the rear side panel 6 and is provided with sidepanels 14, which, when the lid is closed, is swung down to a positionoutside the upper ends of the side panels of the box, whilecorrespondingly the lid front side 10 will cover an upper portion 16 ofthe front side panel 4. This portion 16 is pressed slightly rearwardlyrelative to the underlying part of the panel 4, such that the lid frontside 10, which is a double carton layer, will project only moderately infront of the front panel surface of the box.

For snap locking of the lid in the closed position thereof there isprovided, on the interior side of the lid front panel 10, a projectinglocking edge 18, FIG. 4, cooperating with the top edge 20 of an oblonghole 22 in the upper front panel portion 16. The shaping of the lockingedge 18 will now be described with reference to FIGS. 1-3:

On the box blank the front panel 10 of the lid is extended upwardly intoa free flap 24 consisting of two side portions 26 and and a shorterprojecting intermediate portion 28, the latter terminating in thealready mentioned edge 18, which forms a convex arc of a circle withrounded transitions 30 to the interior side edges of the side portions26. In a practical example, where the height of the lid front panel 10is 15 mm, the bottom of the transitions 30 may be located 3 mm from thefolding line, f, between the portions 10 and 24, while the top height ofthe arched edge 18 above the same line is 5 mm and the width of thearched edge 18 is 20 mm.

The blank is prepared for the erection of the box by folding the flap 24inwardly and downwardly over the panel 10 and, as shown in FIG. 2,arranging for the side portions 26 to be sealed to the panel 10 by thisfolding, while the middle portion 28 is not sealed. This portion,therefore, will seek to fold itself back by virtue of the resiliency ofor in the folding, i.e. the edge 18 will lift itself somewhat--or rathernot be pressed entirely down at the middle of the portion 28. In FIG. 3it is shown by a dotted line how the edge 18 would be located by a totalfolding down against the panel 10, and it will be noted that the edge 18is projecting therefrom and shaped so as to be farthest projecting byits middle portion and to extend double-curved therefrom both outwardlytowards the folding line f and inwardly towards the transition areas 30.Thus, the flap portion 28 will occur as a section of a conical surface,and since the side portions 26 are fixed to the panel 10 the doublearched edge 18 will thus be strongly stabilized both against beingbroken outwardly and against being permanently pressed inwardly.

As shown in FIG. 5 the middle area of the projecting edge 18 is providedat a place just next to the top edge 20 of the slot hole 22 in the upperfront panel 16 of the box, and when the lid is closed there will beestablished at this place a snap locking engagement between these edges,as illustrated in FIG. 6.

When the front side of the lid is pushed upwardly this engagement willbe released by the front panel portion 16 yielding resiliently inwardly,just as it will yield correspondingly for reestablishing the lockingengagement by a subsequent closing of the lid.

Seen from the outside this locking system will reveal itself only by theoccurance of the slot hole 22 in the panel portion 16, but this will bewithout any kind of real disadvantage. Moreover, it will not benecessary to make use of an open hole, as a non-perforated carton layercould be arranged at the rear side of the panel portion 16, whereby thelocking edge 18 could still cooperate with with the edge 20 of the hole22 in the foremost panel layer.

The locking engagement may also be released by a rather pronouncedpressing in of the middle area of the front panel portion of the box,whereby the lid will then pivot somewhat upwardly by virtue of theresiliency in the folding between the rear box panel and the top panelof the lid.

It should be mentioned that a remarkably strong locking engagement willbe achievable between two mutually inverted bulging formations 28.

The use of the disclosed locking engagement will not exclude anadditional use of other kinds of engagements, for example betweenprojecting ear flaps 13 on the side edges of the front panel portion 16,see FIG. 4, and an edge portion 15 of one of the side flaps of the lid.

We claim:
 1. A carton box of the pivot lid type, in which an open end ofthe box is covered by a lid member, which is pivotal outwardly andupwardly about a hinge line at a rear side of the box, while at itsremaining three sides it has depending skirt portions, which in a closedcondition of the lid are projecting inwardly or downwardly so as tooverlap a mouthing area of the box in an overlapping area, whereas at atleast one place in the overlapping area there is provided a snap lockingconnection between the box and the lid by means of a locking nose whichis arranged projecting from an inner side of a front skirt portion ofthe lid and is engageable with a locking edge on an opposed part of afront panel of the box, said locking nose being of the type formed byfolding-over of an edge flap, outer side portions of which are fixedface-to-face to an underlying skirt portion while an intermediatelocking nose portion is left slightly bulging out from said underlyingskirt portion, characterized in that the locking nose portion is shapedwith a convex, arched, free outer edge enabling the locking nose portionto engage into at least a depression defining the locking edge andhaving a width dimension of the same magnitude as that of the lockingnose portion itself.
 2. A box according to claim 1, in which the outerside portions project longer outwardly than the locking nose portion,and in which the occurring corners between outer edges of the lockingnose portion and inner side edges of the outer side portions are softlycurved.
 3. A carton box of the pivot lid type, in which an open end ofthe box is covered by a lid member, which is pivotal outwardly andupwardly about a hinge line at a rear side of the box, while at itsremaining three sides it has depending skirt portions, which in a closedcondition of the lid are projecting inwardly or downwardly so as tooverlap a mouthing area of the box in an overlapping area, whereas at atleast one place in the overlapping area there is provided a snap lockingconnection between the box and the lid by means of a locking nose whichis arranged projecting from an inner side of a front skirt portion ofthe lid and is engageable with a locking edge on an opposed part of afront panel of the box, said locking nose being of the type formed byfolding-over of an edge flap, outer side portions of which are fixedface-to-face to an underlying skirt portion while an intermediatelocking nose portion is left slightly bulging out from said underlyingskirt portion, in which the width dimension of the locking nose portionis small enough to make the outbulging curved/conical all over thewidth, sufficient to stabilize the nose portion in a rigidthree-dimensional shape.
 4. A box according to claim 1, in which thelocking edge as formed by a slot in the front panel of the box has alength that is less than half the width of the front panel.
 5. A boxaccording to claim 1, in which the locking nose cooperates with atransverse narrow slot in the front panel of the box, the width of thisslot being noticeably smaller than the length of a middle portion of thelocking nose as projecting obliquely from its base edge.
 6. A boxaccording to claim 1, in which the locking edge is defined by an openslot.
 7. A box according to claim 1, in which the opposed part of thefront panel comprises two layers, the locking edge comprising a slotthrough a first of the two layers, the slot having a solid backingcomprised of the second of the two layers.